Laminated film or sheet and box-shaped vessel prepared therefrom

ABSTRACT

Disclosed is a laminated film or sheet comprising poly-4-methyl-1-pentene laminated on a paper layer. By using poly-4-methyl-1-pentene having a low melting point, formation of cracks and other defects in the resin layer is prevented and the oil and fat impermeability is improved. If an intermediate layer of a specific polymer is formed in addition to the poly-4-methyl-1-pentene layer, the oil and fat impermeability is further improved. A box-shaped vessel (carton) and a release paper for an artificial leather can be prepared from this laminated film or sheet.

This application is a continuation of application Ser. No. 07/509,302,filed Apr. 16, 1990, now abandoned.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates to a film or sheet composed of a laminatecomprising a layer of a specific resin and a paper layer, and abox-shaped vessel (hereinafter referred to as "carton") prepared fromthis film or sheet.

More particularly, the present invention relates to a film or sheethaving an excellent oil and fat impermeability, which is composed of alaminate comprising a layer of poly-4-methyl-1-pentene having a meltingpoint within a specific range and a paper layer, or a laminatecomprising a layer of ordinary poly-4-methyl-1-pentene, an intermediatelayer of a specific resin and a paper layer, and also to a cartonprepared from this film or sheet.

(2) Description of the Related Art

Recently, the cooking method using an electronic oven has made a rapidprogress, and a variety of foods such as dishes and cakes can be easilyprepared by using an electronic oven.

When a food is cooked by an electronic oven, the food to be cooked iscontained in a tray-shaped vessel formed of a laminate comprising, forexample, an inner layer of a 4-methyl-1-pentene polymer and an outerpaper layer, and the food is subjected to high-frequency heating.

Foods to be cooked include foods containing oil and fat components suchas butter and margarine, for example, pound cakes, and foods on which asauce containing oil and fat components is poured to complete cookingafter heating, and it sometimes happens that after heating in anelectronic oven or after pouring of a sauce containing oil and fatcomponents after side heating, foods are preserved in a box-shapedvessel.

Since the heretofore used covering layer of a 4-methyl-1-pentene polymerhas a high rigidity, fine cracks are sometimes formed in the coveringlayer. Moreover, when oil and fat components as described above arepresent, they permeate into the paper layer constituting the vessel withthe lapse of time, the paper layer as a whole becomes oily to degradethe appearance of the vessel, and there is a risk of contamination ofthe hand or clothing with oil and fat components at the time ofhandling.

SUMMARY OF THE INVENTION

It is a primary object of the present invention to provide a laminatedfilm or sheet in which formation of cracks in the covering layer isprevented so that permeation of oil and fat components from a containedcooked food is prevented, and a carton prepared from this film or sheet.

Another object of the present invention is to provide a laminated filmor sheet in which by forming an intermediate layer of a specific resinin addition to a covering layer of a 4-methyl-1-pentene polymer,permeation of oil and fat components from a contained cooked food can beprevented, and a carton prepared from this laminated film or sheet.

In accordance with one fundamental aspect of the present invention, theforegoing objects can be attained by providing a laminated film or sheethaving at least two layers, which comprises (A) a layer ofpoly-4-methyl-1-pentene having a melting point of 190° to 230° C. and(B) a paper layer.

In accordance with another aspect of the present invention, there isprovided a laminated film or sheet having at least three layers, whichcomprises (A) a layer of poly-4-methyl-1-pentene, (B) an intermediatelayer of a propylene polymer and (C) a paper layer.

In this laminated film or sheet, the melting point of thepoly-4-methyl-1-pentene constituting the inner layer is generally 190°to 245° C. and preferably 200° to 235° C. The propylene polymerconstituting the intermediate layer is a propylene homopolymer orpropylene/ethylene random copolymer having MFR (melt flow rate) of 1 to200 g/10 min, preferably 10 to 100 g/100 min.

In accordance with still another aspect of the present invention, thereis provided a laminated film or sheet having at least three layers,which comprises (A) a layer of poly-4-methyl-1-pentene, (B) anintermediate layer of a polyester type polymer and (C) a paper layer.

In this laminated film or sheet comprising the above-mentionedintermediate layer, the permeation of oil and fat components into thepaper layer is further prevented, and a carton having an excellent oilresistance can be prepared from this laminated film or sheet.

In accordance with still another aspect of the present invention, thereis provided a laminated film or sheet having at least three layers,which comprises (A) a layer of poly-4-methyl-1-pentene having a highmelting point, (B) an intermediate layer of poly-4-methyl-1-pentenehaving a low melting point and (C) a paper layer.

The melting point of the high-melting-point poly-4-methyl-1-penteneconstituting one layer of this laminated film or sheet is 220° to 245°C., and the melting point of the low-melting-pointpoly-4-methyl-1-pentene constituting the intermediate layer is 190° to230° C.

If the covering layer is divided into two layers composed ofpoly-4-methyl-1-pentenes differing in the characteristics and theintermediate layer is formed of poly-4-methyl-1-pentene having a lowmelting point, the resistance to permeation of oil and fat components ishighly improved.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the laminated film or sheet of the present invention, the coveringlayer is formed of poly-4-methyl-1-pentene.

The poly-4-methyl-1-pentene used in the present invention is ahomopolymer of 4-methyl-1-pentene or a copolymer of 4-methyl-1-pentenewith up to 20 mole %, preferably up to 12 mole % of an α-olefin having 2to 20 carbon atoms, such as ethylene, propylene, 1-butene, 1-hexene,1-octene, 1-decene, 2-tetradecene or 1-octadecene. Crystallinepoly-4-methyl-1-pentene having a melting point of 190° to 230° C. ispreferably used. This polymer can be prepared according to a knownprocess, for example, the process disclosed in Japanese UnexaminedPatent Publication No. 59-206418. MFR of the poly-4-methyl-1-pentene ispreferably 5 to 1000 g/10 min, and poly-4-methyl-1-pentene having MFR of70 to 300 g/10 min is especially preferably used because moldability andheat resistance are very good.

In general, increase of the amount of the α-olefin to be copolymerizedresults in lowering of the melting point, but the melting point isinfluenced by the kind of the α-olefin, the catalyst used and otherpolymerization conditions. However, since the relations of these factorsto the melting point can be experimentally determined in advance,persons skilled in the art will easily obtain poly-4-methyl-1-pentenehaving a desired melting point.

If a layer of poly-4-methyl-1-pentene having a relatively low meltingpoint of 190° to 230° C. is laminated with a paper layer, even underheating in an electronic oven, the above-mentioned oil and fatcomponents are not allowed to permeate into the paper layer, andtherefore, a laminated film or sheet suitable as a vessel material canbe provided.

Papers customarily used as the material for boxes or cases, such asclay-coated paper and milk carton paper, can be used as the paperconstituting the paper layer. However, use of clay-coated paper isrecommended because the permeation rate of oil and fat components can bemaintained at a very low level even if pinholes or small cracks areformed in the poly-4-methyl-1-pentene layer by unexpected shock orrubbing or even if the oil and fat components happen to permeate fromthe end face of the laminated film or sheet. Moreover, since thisclay-coated paper is excellent in the printability, the laminated sheetor film is suitably used as a base material to be printed when a printlayer is formed on the surface of the vessel according to need.

The laminated film or sheet of the present invention can be prepared byextrusion-coating poly-4-methyl-1-pentene directly on the surface ofpaper, or by extrusion-coating poly-4-methyl-mentene on the surface ofpaper which has been subjected to an adhesiveness-increasing treatmentaccording to a known method, for example, by coating the paper surfacewith an anchor coat agent of an organic titanium, polyethyleneimine orisocyanate type or bonding an adhesive polyolefin or high-pressurepolyethylene as the undercoat to the paper surface. In the latter case,a laminated film or sheet having a three-layer structure is obtained.

Formation of Laminated Film or Sheet

The poly-4-methyl-1-pentene constituting the inner layer of the laminateof the present invention is excellent in the adaptability to extrusioncoating at a high speed, and therefore, the poly-4-methyl-1-pentene canbe extrusion-coated at a high speed by using an ordinaryextrusion-coating apparatus. By this extrusion coating a laminated filmor sheet having excellent mechanical properties and interlaminaradhesiveness can be obtained. If a gas such as air or nitrogen gas isblown to both the ends of the extruded film or sheet at the extrusioncoating, neck-in or edge wave at both the ends of the extruded film orsheet can be prevented, and in this case, if blowing of the gas iseffected in the vicinity of the point of the contact of the extrudedfilm or sheet with the paper substrate from the side where the extrudedfilm or sheet is not contacted with the paper substrate, the extrusioncoating is accomplished at a high speed more stably.

As the method for blowing a gas to the extruded film or sheet, there canbe mentioned a method in which a metal tube such as an aluminum tube orcopper tube or a conduit tube such as a thermoplastic resin tube isarranged downstream of a die, and a gas is blown to the extruded film orsheet of poly-4-methyl-1-pentene at an optional point in the course ofup to the point of the contact of the film or sheet extruded from thedie with the paper substrate, preferably in the vicinity of the contactpoint where the extruded film or sheet is coated on the paper substrate.The pressure of the gas to be blown is appropriately determined in viewof the thickness of the extruded film or sheet to be coated. However,the pressure of the gas is generally 0.5 to 5 kg/cm² G. The aperture ofthe top end of a nozzle for blowing the gas is generally 1 to 50 mm² andpreferably 5 to 10 mm². The distance between the top end of the nozzleand the extruded film or sheet is generally 2 to 100 mm and preferably 5to 20 mm. If the top end of the blowing nozzle is directed to the outerside of the extruded film or sheet from the inner side thereof, the filmor sheet is expanded by the blown gas and the effect of furthernarrowing neck-in is preferably attained.

When the poly-4-methyl-1-pentene constituting the inner layer isextrusion-coated, the extrusion temperature is ordinarily 250° to 370°C. and preferably 290° to 340° C. The extrusion-coating speed (thetake-up speed of the covering material) is generally at least 100 m/minand preferably 150 to 500 m/min. The thickness of thepoly-4-methyl-1-pentene layer and paper are not particularly critical,but the thickness of the poly-4-methyl-1-pentene and paper layers aregenerally 1 to 2000 μm and 5 to 5000 μm, respectively, and preferably 5to 50 μm and 100 to 600 μm, respectively.

Known additives such as a weathering stabilizer, a heat stabilizer, anantistatic agent, an antifogging agent, an antiblocking agent, a slipagent and a colorant can be incorporated into thepoly-4-methyl-1-pentene used in the present invention, so far as theintended objects of the present invention can be attained.

Film or Sheet Comprising Intermediate Layer

In the case where a resin layer of a propylene polymer or polyester typepolymer is formed as the intermediate layer, poly-4-methyl-1-pentenehaving an ordinary melting point, for example, a melting point of 190°to 245° C. is used. The kinds of the poly-4-methyl-1-pentene andcomonomer are the same as described above. The same paper layer asdescribed above is used.

(1) Intermediate Layer of Propylene Polymer

The propylene polymer constituting the intermediate layer in the presentinvention includes a crystalline homopolymer having MFR of 1 to 200 g/10min, preferably 10 to 100 g/10 min, and a crystalline copolymer ofpropylene with up to 15 mole % of other olefin such as ethylene,1-butene, 1-hexene, 4-methyl-1-pentene or 1-octene.

Since the poly-4-methyl-1-pentene and propylene polymer constituting theouter layer (covering layer) and intermediate layer in the presentinvention have an excellent adaptability to the extrusion coating at ahigh speed, the extrusion coating can be performed at a high speed, asdescribed hereinbefore.

Furthermore, as described hereinbefore, neck-in or edge wave on both theends of the extruded film or sheet can be prevented by blowing a gassuch as air or nitrogen gas to both the ends of the extruded film orsheet.

The above-mentioned method can be similarly adopted for blowing the gasto the extruded film or sheet, and the extrusion temperature forextrusion-coating the poly-4-methyl-1-pentene and propylene polymer isthe same as the above-mentioned extrusion temperature adopted for thetwo-layer film or sheet.

In the laminated film or sheet of the present embodiment, thethicknesses of the poly-4-methyl-1-pentene layer, propylene polymerlayer and paper layer can be optionally selected, but the thicknesses ofthe poly-4-methyl-1-pentene layer, propylene polymer layer and paperlayer are generally 1 to 2000 μm, 1 to 2000 μm and 5 to 5000 μm,respectively, and preferably 5 to 50 μm, 5 to 50 μm and 100 to 600 μm,respectively.

Known additives such as a weathering stabilizer, a heat stabilizer, anantistatic agent, an antifogging agent, an antiblocking agent, a slipagent and a colorant can be incorporated in each of thepoly-4-methyl-1-pentene and propylene polymer used in the presentinvention, so far as the attainment of the intended objects of thepresent invention is not inhibited.

According to this embodiment of the present invention, by adopting alaminate structure of poly-4-methyl-1-pentene layer/propylene polymerlayer/paper layer for the laminated film or sheet, even if oil and fatcomponents fall in contact with the poly-4-methyl-1-pentene layer, thepermeation of these components can be completely prevented. A cartonprepared from this laminated film or sheet shows an excellent oilresistance, and therefore, this carton can be advantageously used as atray to be used for cooking in an electronic oven, a carton for a foodcontaining oil and fat components, such as a cake or a bun, and otherpackaging vessels.

(2) Intermediate Layer of Polyester Type Polymer

The polyester type polymer constituting the intermediate layer in thepresent invention is a thermoplastic polyester resin comprising mainrecurring units of ethylene terephthalate or butylene terephthalate andhaving an intrinsic viscosity [η] of 0.4 to 1.5 dl/g, preferably 0.5 to1.2 dl/g, and a melting point of 210° to 265° C., preferably 220° to260° C., which is derived from terephthalic acid as the main acidcomponent and a diol such as ethylene glycol or 1,4-butane-diol as themain polyhydric alcohol component. Polyethylene terephthalate ispreferably used since this polyester has an excellent extrusionlamination processability.

The laminated film or sheet of the present embodiment can be prepared byextrusion-coating poly-4-methyl-1-pentene and an intermediatelayer-forming polyester directly on paper by co-extrusion.Alternatively, there can be adopted a method in which in order tofurther increase the adhesion strength between the paper andintermediate layer, according to a known method, the paper surface iscoated with an anchor coat agent of an organic titanium,polyethyleneimine or isocyanate type or an adhesive polyethylene orhigh-pressure polyethylene is coated as the undercoat on the papersurface, and the poly-4-methyl-1-pentene and polyester type polymer areextrusion-coated on the treated paper surface. In the latter case, alaminated film or sheet having a four-layer structure is obtained.

In the present embodiment, the poly-4-methyl-1-pentene and polyestertype polymer are extrusion-coated by the same extrusion-coating methodas adopted in the above embodiment using the propylene type polymer forthe intermediate layer, and the gas-blowing conditions and extrusiontemperature are substantially the same as adopted in the above-mentionedembodiment using the propylene polymer.

In the laminated film or sheet of the present embodiment, the thicknessof the poly-4-methyl-1-pentene layer, polyester polymer layer and paperlayer can be optionally selected, but the thickness of thepoly-4-methyl-1-pentene layer, polyester polymer layer and paper layerare generally 1 to 2000 μm, 1 to 2000 μm and 5 to 5000 μm, respectively,and preferably 5 to 50 μm, 5 to 50 μm and 100 to 600 μm, respectively.

Known additives such as a weathering stabilizer, a heat stabilizer, anantistatic agent, an antifogging agent, an antiblocking agent, a slipagent and a colorant can be incorporated in each of thepoly-4-methyl-1-pentene and polyester polymer used in the presentinvention, so far as the attainment of the intended objects of thepresent invention is not inhibited.

According to this embodiment of the present invention, by adopting alaminate structure of poly-4-methyl-1-pentene layer/polyester polymerlayer/paper layer for the laminated film or sheet, even if oil and fatcomponents fall in contact with the poly-4-methyl-1-pentene layer, thepermeation of these components can be completely prevented. A cartonprepared from this laminated film or sheet shows an excellent oilresistance, and therefore, this carton can be advantageously used as atray to be used for cooking in an electronic oven, a carton for a foodcontaining oil and fat components, such as a cake or a bun, and otherpackaging vessels.

(3) Laminate Comprising Two Poly-4-methyl-1-pentene Layers

In this embodiment, a crystalline homopolymer of 4-methyl-1-pentene or acrystalline copolymer of 4-methyl-1-pentene with up to 20 mole %,preferably up to 12 mole %, of other α-olefin such as ethylene,propylene, 1-butene, 1-hexene, 1-octene, 1-decene, 1-tetradecene or1-octadecene, which has a melting point of 220° to 245° C., especially225° to 240° C., is preferably used as the high-melting-pointpoly-4-methyl-1-pentene. This polymer can be prepared according to aknown process, for example, the process disclosed in Japanese UnexaminedPatent Publication No. 59-206418. MFR of the high-melting-pointpoly-4-methyl-1-pentene is preferably 5 to 1000 g/10 min, andpoly-4-methyl-1-pentene having MFR of 70 to 300 g/10 min is especiallypreferably used since the moldability and heat resistance are very good.

MFR of the low-melting-point poly-4-methyl-1-pentene is within the samerange as that of the above-mentioned high-melting-point ofpoly-4-methyl-1-pentene, but the melting point is 190° to 230° C.,preferably 200° to 230° C. Also this polymer can be prepared accordingto the process disclosed in Japanese Unexamined Patent Publication No.59-206418. A polymer having a melting point within the above-mentionedrange can be obtained by increasing the amount copolymerized of theα-olefin over the amount of the comonomer used for the production of thehigh-melting-point poly-4-methyl-1-pentene.

In general, increase of the amount of the α-olefin to be copolymerizedresults in lowering of the melting point, but the melting point isinfluenced by the kind of the α-olefin, the catalyst use otherpolymerization conditions. However, since the relations of these factorsto the melting point can be experimentally determined in advance,persons skilled in the art will easily obtain poly-4-methyl-1-pentenehaving a desired melting point.

As is apparent from the foregoing description, there is a substantialdifference of the melting point between the high-melting-point andlow-melting-point poly-4-methyl-1-pentenes used in this embodiment ofthe present invention. The melting point ranges of both the polymerspartially overlap each other, but it is indispensable that thehigh-melting-point poly-4-methyl-1-pentene should have a melting pointhigher than the melting point of the low-melting-pointpoly-4-methyl-1-pentene constituting the intermediate layer.

In the present embodiment, by forming one layer of high-melting-pointpoly-4-methyl-1-pentene having a higher rigidity and an intermediatelayer of poly-4-methyl-1-pentene having a lower melting point and alower rigidity, even if the laminated film or sheet is heated in anelectronic oven, oil and fat components as mentioned above are notallowed to permeate into another layer, that is, the paper layer,through these two layers, and therefore, the laminated film or sheet isvery suitable as a material for a vessel.

The extrusion temperature adopted for extrusion-coating twopoly-4-methyl-1-pentenes constituting the inner and intermediate layerson the paper substrate is generally 250° to 370° C. and preferably 290°to 340° C. The extrusion-coating speed (the take-up speed of thecovering material) is generally at least 100 m/min and preferably 150 to500 m/min.

In the laminated film or sheet of the present embodiment, the thicknessof the high-melting-point poly-4-methyl-1-pentene layer,low-melting-point poly-4-methyl-1-pentene layer and paper layer can beoptionally selected, but the thickness of the high-melting-pointpoly-4-methyl-1-pentene layer, low-melting-point poly-4-methyl-1-pentenelayer and paper layer are generally 1 to 2000 μm, 1 to 2000 μm and 5 to5000 μm, respectively, and preferably 5 to 50 μm, 5 to 50 μm and 100 to600 μm, respectively.

Known additives such as a weathering stabilizer, a heat stabilizer, anantistatic agent, an antifogging agent, an antiblocking agent, a slipagent and a colorant can be incorporated in each of the twopoly-4-methyl-1-pentenes used in the present invention, so far as theattainment of the intended objects of the present invention is notinhibited.

According to this embodiment of the present invention, by adopting alaminate structure of high-melting-point poly-4-methyl-1-pentenelayer/low-melting-point poly-4-methyl-1-pentene layer/paper layer forthe laminated film or sheet, even if oil and fat components fall incontent with the high-melting-point poly-4-methyl-1-pentene layer, thecarton prepared from this laminate film or sheet shows an excellent oilresistance, and therefore, this carton can be advantageously used as atray to be used for cooking in an electronic oven, a carton for a foodcontaining oil and fat components, such as a cake or a bun, and otherpackaging vessels.

Since the laminated film or sheet of the present invention has excellentoil resistance and heat resistance, the laminated film or sheet can beadvantageously used as release paper for the production of an artificialleather. More specifically, the laminated film or sheet is passedthrough between a nip roll and an embossing roll to form aconvexity-concavity embossed pattern or grain pattern on the surface ofthe poly-4-methyl-1-pentene layer, and the patterned surface of thepoly-4-methyl-1-pentene layer is coated with a PVC sol or polyurethanesolution as the starting material of an artificial leather. The obtainedthree-layer laminate is heated in an oven to cure the PVC orpolyurethane layer. Then, the release paper comprising thepoly-4-methyl-1-pentene and paper is peeled from the obtainedthree-layer cured body, whereby an artificial leather member composed ofPVC or polyurethane, which has the embossed pattern or grain patterntransferred on the surface thereof, can be obtained.

Since this release paper for an artificial leather is heated for curingthe PVC or polyurethane layer coated on the surface thereof, the releasepaper should have an excellent heat resistance. Since thepoly-4-methyl-1-pentene constituting the outer layer of the laminatedfilm or sheet of the present invention has a high melting point, a highheat resistance can be manifested.

When the PVC or polyurethane layer having the embossed or grain patterntransferred thereon is separated by peeling, there is a risk of thepattern-forming outer layer of the poly-4-methyl-1-pentene together withthe PVC or polyurethane layer. However, in the present invention, sincethe outer layer and paper layer are tightly bonded to each other throughthe intermediate layer of the low-melting-point poly-4-methyl-1-pentene,peeling of the outer layer together with the PVC or polyurethane layercan be prevented. Accordingly, the laminated film or sheet of thepresent invention can be used as an excellent release paper for anartificial leather.

The present invention will now be described in detail with reference tothe following examples that by no means limit the scope of theinvention.

In the examples, the melting point, MFR and initial modulus ofelasticity were measured according to the following methods.

Melting Point

By using a differential scanning calorimeter (model DSC-II supplied byPerkin-Elmar), a sample was melting at 260° C. for 5 minutes, cooled toroom temperature at a rate of 20° C./min to effect crystallization andmaintained at room temperature, an endothermic curve was determined at atemperature-elevating rate of 10° C./min, and the peak temperature wasdesignated as the melting point. The poly-4-methyl-1-pentene used in thepresent invention shows one endothermic peak or a plurality ofendothermic peaks. When a plurality of peaks were observed, the highestpeak temperature was designated as the melting point.

MFR

The MFR value was measured under a load of 5 kg at 260° C. according toASTM D-1238.

Initial Modulus of Elasticity

The initial modulus of elasticity was measured according to ASTM S-790(the test speed was adjusted to 5 mm/min).

MFR of Polypropylene

MFR of polypropylene was measured under a load of 2.16 kg at 230° C.according to ASTM D-1238.

Intrinsic Viscosity [η] of polyethylene Terephthalate Resin

The intrinsic viscosity of a polyethylene terephthalate resin wasmeasured at a temperature of 23° C. in a phenol/tetrachloroethane mixedsolvent (weight ratio=1/1)

EXAMPLE 1

A crystalline copolymer of 4-methyl-1-pentene with 1-octadecene(1-octadecene content of 6% by weight) [hereinafter referred to as "PMP(1)"] having a melting point of 226° C., MFR of 26 g/10 min and aninitial flexural modulus of elasticity of 5000 kg/cm² was melted in anextruder having a screw diameter of 65 mm and laminated on a milk cartonpaper having a base weight of 290 g/m². The coating thickness of PMP (1)was 20 μm A case having a size of 10 cm×10 cm×5 cm (depth) was preparedfrom the laminated paper so that the coating layer was located on theinner surface.

Then, weighed 40 g of commercially available margarine (supplied byYukijirushi Nyugyo) was placed in the case and heated for 30 seconds byan electronic oven (Type NE-A740 supplied by Matsushita Denki Sangyo).After the heating, the case was allowed to stand still at roomtemperature, and the number of days required for the margarine to exudeto the outer surface of the paper layer was determined by the visualinspection.

A case prepared in the same manner as described above was charged with astarting powder of a chocolate cake (House Range Gourmet supplied byHouse Shokuhin) and water, and cooking was carried out for 3 minutes and30 seconds by using the same electronic oven as described above. Afterthe cooking, exudation of the content to the outer surface was examinedwithout taking out the content from the case.

Similarly, a case prepared in the same manner as described above wascharged with a starting powder of butter cake (House Range Gourmetsupplied by House Shokuhin) and water, and cooking was carried out at aset temperature of 190° C. for 20 minutes in an oven. After the cooking,exudation of the content to the outer surface was examined withouttaking out the content from the case.

The obtained results are shown in Table 1.

EXAMPLE 2

The procedures of Example 1 were repeated in the same manner except thata crystalline copolymer of 4-methyl-1-pentene with decene (decenecontent=8% by weight) [hereinafter referred to as "PMP (II)"] having amelting point of 221° C., MFR of 26 g/10 min and an initial flexuralmodulus of elasticity of 400 kg/cm² was used instead of PMP (I) used inExample 1.

The obtained results are shown in Table 1.

Comparative Example 1

The procedures of Example 1 were repeated in the same manner except thata homopolymer of 4-methyl-1-pentene [hereinafter referred to as "PMP(H)"] having a melting point of 242° C., MFR of 26 g/10 min and aninitial flexural modulus of elasticity of 19000 kg/cm² was used insteadof PMP (I) used in Example 1.

The obtained results are shown in Table 1.

Comparative Example 2

The procedures of Example 1 were repeated in the same manner except thata crystalline copolymer of 4-methyl-1-pentene with 1-decene (1-decenecontent of 2.5% by weight) [hereinafter referred to as "PMP (III)"]having a melting point of 237° C., MFR of 180 g/10 min and an initialflexural modulus of elasticity of 13000 kg/cm² was used instead of PMP(I) used in Example 1.

The obtained results are shown in Table 1.

                  TABLE 1                                                         ______________________________________                                               Example                                                                              Example  Comparative                                                                              Comparative                                        1      2        Example 1  Example 2                                   ______________________________________                                        Structure                                                                     coating resin                                                                          PMP(I)   PMP(II)  PMP (H)  PMP(III)                                  coating  20 μm 20 μm 20 μm 20 μm                                  thickness                                                                     Number of                                                                              exudation                                                                              same as  2        4                                         days for was not  in                                                          exudation of                                                                           caused   Example                                                     margarine                                                                              for 20   1                                                           (electronic                                                                            days, and                                                            oven)    test was                                                                      stopped                                                              Number of                                                                              exudation                                                                              same as  1        3                                         days for was not  in                                                          exudation of                                                                           caused   Example                                                     chocolate                                                                              for 20   1                                                           cake (electro-                                                                         days, and                                                            nic oven)                                                                              test was                                                                      stopped                                                              Number of                                                                              exudation                                                                              same as  1        3                                         days for was not  in                                                          exudation of                                                                           caused   Example                                                     butter cake                                                                            for 20   1                                                           (oven)   days, and                                                                     test was                                                                      stopped                                                              ______________________________________                                    

EXAMPLE 3

PMP (III) in Comparative Example 2 and a propylene homopolymer[hereinafter referred to as "PP (1)"] having MFR of 30 g/10 min wereindependently melted in extruders having a screw diameter of 65 mm, andthe melts were laminated on a milk carton paper having a base weight of290 g/mm² by using a coextrusion two-layer die. The total coatingthickness was 30 μm and each of the coating layers had a thickness of 15μm. A case having a size of 10 cm×10 cm×5 cm (depth) was prepared fromthe obtained laminated paper so that the coating layer was located onthe inner surface.

Then, weighed 40 g of commercially available margarine (supplied byYukijirushi Nyugyo) was placed in the case and heated for 30 seconds byan electronic oven (Type NE-A740 supplied by Matsushita Denki Sangyo).After the heating, the case was allowed to stand still at roomtemperature, and the number of days required for the margarine to exudeto the outer surface of the paper layer was determined by the visualinspection.

A case prepared in the same manner as described above was charged with astarting powder of a chocolate cake (House Range Gourmet supplied byHouse Shokuhin) and water, and cooking was carried out for 3 minutes and30 seconds by using the same electronic oven as described above. Afterthe cooking, exudation of the content to the outer surface was examinedwithout taking out the content from the case.

Similarly, a case prepared in the same manner as described above wascharged with a starting powder of butter cake (House Range Gourmetsupplied by House Shokuhin) and water, and cooking was carried out at aset temperature of 190° C. for 20 minutes in an oven. After the cooking,exudation of the content to the outer surface was examined withouttaking out the content from the case.

The obtained results are shown in Table 2.

EXAMPLE 4

The procedures of Example 3 were repeated in the same manner except thatthe coating thickness of PMP (III) used in Example 2 was changed to 10μm and the coating thickness of PP (I) was changed to 20 μm. Theobtained results are shown in Table 2.

EXAMPLE 5

The procedures of Example 3 were repeated in the same manner except thatethylene/propylene random copolymer having ethylene content of 5% byweight [hereinafter referred to as "PP (II)"] was used instead of PP (I)used in Example 3. The obtained results are shown in Table 2.

Comparative Example 3

The procedures of Example 3 were repeated in the same manner except thata resin mixture comprising PMP (III) and PP (I) at a ratio of 3/1 wasused instead of PP (I) used in Example 3. The obtained results are shownin Table 2.

Comparative Example 4

The procedures of Example 3 were repeated in the same manner except thata resin mixture comprising PMP (III) and PP (I) at a ratio of 1/1 wasused instead of PP (I) used in Example 3, whereby a product having atotal coating thickness of 30 μm was obtained.

The exudation test was carried out in the same manner as described inExample 3. The obtained results are shown in Table 2.

Comparative Example 5

By using a single-layer die instead of the coextrusion two-layer dieused in Example 3, PMP (III) was laminated in a coating thickness of 15μm. Then, PMP (III) was laminated again in a thickness of 15 μm whileopening a roll of the semi-finished product once wound to obtain aproduct having a total coating thickness of 30 μm. Also this product wassubjected to the exudation test in the same manner as described inExample 3. The obtained results are shown in Table 2.

                                      TABLE 2                                     __________________________________________________________________________                                  Comparative                                                                             Comparative                                                                             Comparative                         Example 3 Example 4                                                                           Example 5                                                                           Example 3 Example 4 Example                     __________________________________________________________________________                                                      5                           Structure                                                                     inner layer                                                                           PMP (III) PMP (III)                                                                           PMP (III)                                                                           PMP (III) PMP (III) PMP (III)                   intermediate                                                                          PP (I)    PP (I)                                                                              PP (II)                                                                             PMP (I) + PP (I)                                                                        PMP (I) + PP (I)                                                                        PMP (I)                     layer                          (75)   (25)                                                                             (50)   (50)                          outer layer                                                                           milk carton                                                                             milk carton                                                                         milk carton                                                                         milk carton                                                                             milk carton                                                                             milk carton                         paper     paper paper paper     paper     paper                       Thickness (μm)                                                             inner layer                                                                            15        10    15    15        15        15                         intermediate                                                                           15        20    15    15        15        15                         layer                                                                         outer layer                                                                           300       300   300   300       300       300                         Number of days                                                                        exudation was not                                                                       same as in                                                                          same as in                                                                           1         2         4                          for exudation of                                                                      caused for 20 days,                                                                     Example 3                                                                           Example 3                                             margarine                                                                             and test was stopped                                                  Number of days                                                                        exudation was not                                                                       same as in                                                                          same as in                                                                            3        3         3                          for exudation of                                                                      caused for 20 days,                                                                     Example 3                                                                           Example 3                                             chocolate cake                                                                        and test was stopped                                                  Number of days                                                                        exudation was not                                                                       same as in                                                                          same as in                                                                           5         5         5                          for exudation of                                                                      caused for 20 days,                                                                     Example 3                                                                           Example 3                                             butter cake                                                                           and test was stopped                                                  __________________________________________________________________________     Note                                                                          Each parenthesized value indicates the blending ratio.                   

EXAMPLE 6

PMP (III) and polyethylene terephthalate [hereinafter referred to as"PET (I)"] having an intrinsic viscosity [η] of 0.6 were independentlymelted in extruders having a screw diameter of 65 mm and the melts werelaminated on milk carton paper having a base weight of 290 g/mm² byusing a coextrusion two-layer die. The total coating thickness was 30μm, and each of the laminated layers had a thickness of 15 μm. A casehaving a size of 10 cm×10 cm×5 cm (depth) was prepared from the obtainedlaminated paper so that the coating layer was located on the innersurface.

Then, weighed 40 g of commercially available margarine (supplied byYukijirushi Nyugyo) was placed in the case and heated for 30 seconds byan electronic oven (Type NE-A740 supplied by Matsushita Denki Sangyo).After the heating, the case was allowed to stand still at roomtemperature, and the number of days required for the margarine to exudeto the outer surface of the paper layer was determined by the visualinspection.

A case prepared in the same manner as described above was charged with astarting powder of a chocolate cake (House Range Gourmet supplied byHouse Shokuhin) and water, and cooking was carried out for 3 minutes and30 seconds by using the same electronic oven as described above. Afterthe cooking, exudation of the content to the outer surface was examinedwithout taking out the content from the case.

Similarly, a case prepared in the same manner as described above wascharged with a starting powder of butter cake (House Range Gourmetsupplied by House Shokuhin) and water, and cooking was carried out at aset temperature of 190° C. for 20 minutes in an oven. After the cooking,exudation of the content to the outer surface was examined withouttaking out the content from the case.

The obtained results are shown in Table 3.

EXAMPLE 7

The procedures of Example 6 were repeated in the same manner except thatthe coating thickness of PMP (III) used in Example 6 was changed to 20μm and the thickness of the coating layer of PET (I) was changed to 10μm. The obtained results are shown in Table 3.

                  TABLE 3                                                         ______________________________________                                                     Example 6   Example 7                                            ______________________________________                                        Structure                                                                     inner layer    PMP(III)(15)  PMP(III)(20)                                     intermediate   PET(I) (15)   PET(I) (10)                                      layer                                                                         outer layer    milk carton   milk carton                                                     paper (300)   paper (300)                                      Number of days for                                                                           exudation was same as in                                       exudation of   not caused for                                                                              Example 6                                        margarine      20 days, and                                                                  test was stopped                                               Number of days for                                                                           exudation was same as in                                       exudation of   not caused for                                                                              Example 6                                        chocolate cake 20 days, and                                                   (electronic oven)                                                                            test was stopped                                               Number of days for                                                                           exudation was same as in                                       exudation of   not caused for                                                                              Example 6                                        butter cake (oven)                                                                           20 days, and                                                                  test was stopped                                               ______________________________________                                         Note                                                                          Unit of each parenthesized value is μm.                               

EXAMPLE 8

PMP (III) in Comparative Example 2 and PMP (I) in Example 1 wereindependently melted in extruders having a screw diameter of 65 mm, andthe melts were laminated on a milk carton paper having a base weight of290 g/mm² by using a coextrusion two-layer die. The total coatingthickness was 30 μm, and each of the coating layers had a thickness of15 μm. A case having a size of 10 cm×10 cm×5 cm (depth) was preparedfrom the obtained laminated paper so that the coating layer was locatedon the inner surface.

Then, weighed 40 g of commercially available margarine (supplied byYukijirushi Nyugyo) was placed in the case and heated for 30 seconds byan electronic oven (Type NE-A740 supplied by Matsushita Denki Sangyo).After the heating, the case was allowed to stand still at roomtemperature, and the number of days required for the margarine to exudeto the outer surface of the paper layer was determined by the visualinspection.

A case prepared in the same manner as described above was changed with astarting powder of a chocolate cake (House Range Gourmet supplied byHouse Shokuhin) and water, and cooking was carried out for 3 minutes and30 seconds by using the same electronic oven as described above. Afterthe cooking, exudation of the content to the outer surface was examinedwithout taking out the content from the case.

Similarly, a case prepared in the same manner as described above wascharged with a starting powder of butter cake (House Range Gourmetsupplied by House Shokuhin) and water, and cooking was carried out at aset temperature of 190° C. for 20 minutes in an oven. After the cooking,exudation of the content to the outer surface was examined withouttaking out the content from the case.

The obtained results are shown in Table 4.

EXAMPLE 9

The procedures of Example 8 were repeated in the same manner except thata crystalline copolymer of 4-methyl-1-pentene with octadecene(octadecene content of 4% by weight) [hereinafter referred to as "PMP(III)"] having a melting point of 229° C., MFR of 10 min and an initialflexural modulus of elasticity of 8000 kg/cm² was used instead of PMP(I) used in Example 1. The obtained results are shown in Table 4.

Comparative Example 6

The procedures of Example 8 were repeated in the same manner except thatPMP (III) used in Example 2 was used for both of the coextruded layers.The obtained results are shown in Table 4.

                  TABLE 4                                                         ______________________________________                                                                     Comparative                                               Example 8 Example 9 Example 6                                        ______________________________________                                        Structure                                                                     inner layer                                                                              PMP(III)    PMP(I)    PMP(III)                                                (15 μm)  (15 μm)                                                                              (15 μm)                                   intermediate                                                                             PMP(I)      PMP(IV)   PMP(I)                                       layer      (15 μm)  (15 μm)                                                                              (15 μm)                                   paper                                                                         Number of days                                                                           exudation was                                                                             same as in                                                                              4                                            for exudation of                                                                         not caused  Example 8                                              margarine  for 20 days,                                                                  and test was                                                                  stopped                                                            Number of days                                                                           exudation was                                                                             same as in                                                                              3                                            for exudation of                                                                         not caused  Example 8                                              chocolate cake                                                                           for 20 days,                                                       (electronic oven)                                                                        and test was                                                                  stopped                                                            Number of days                                                                           exudation was                                                                             same as in                                                                              5                                            for exudation of                                                                         not caused  Example 8                                              butter cake                                                                              for 20 days,                                                       (oven)     and test was                                                                  stopped                                                            ______________________________________                                         Note                                                                          Unit of each parenthesized value is μm.                               

We claim:
 1. A laminated film or sheet having at least two layers, which comprises (A) a layer consisting essentially of poly-4-methyl-1-pentene having a melting point of 190° to 230° C. and (B) a paper layer laminated directly to layer (A).
 2. A laminated film or sheet as set forth in claim 1, wherein the thickness of the layer (A) is 1 to 2000 μm and the thickness of the layer (B) is 5 to 5000 μm.
 3. A laminated film or sheet as set forth in claim 1 or 2, wherein the melt flow rate of the poly-4-methyl-1-pentene is 5 to 1000 g/10 min.
 4. A box-shaped vessel prepared from a laminated film or sheet as set forth in claim
 1. 5. A laminated film or sheet having at least three layers, which comprises (A) a layer consisting essentially of poly-4-methyl-1-pentene, (B) an intermediate layer of a crystalline homopolymer of propylene or a crystalline copolymer comprising at least 85 mole % propylene and up to 15 mole % of another olefin, said intermediate layer (B) being laminated directly to layer (A) and (C) a paper layer laminated to the intermediate layer (B).
 6. A laminated film or sheet as set forth in claim 5, wherein the poly-4-methyl-1-pentene has a melting point of 190° to 245° C.
 7. A laminated film or sheet as set forth in claim 5, wherein the poly-4-methyl-1-pentene has a melting point of 190° to 230° C.
 8. A laminated film or sheet as set forth in claim 5, wherein the intermediate layer is composed of polypropylene having a melt flow rate of 1 to 200 g/10 min.
 9. A laminated film or sheet as set forth in claim 5, wherein the polypropylene layer has a thickness of 5 to 5000 μm.
 10. A box-shaped vessel prepared from a laminated film or sheet as set forth in claim
 5. 11. A laminated film or sheet as set forth in claim 1, wherein said poly-4-methyl-1-pentene having a melting point of 190° to 230° C. is a homopolymer of 4-methyl-1-pentene or a copolymer of 4-methyl-1-pentene with up to 20 mole % of an α-olefin having 2 to 20 carbon atoms.
 12. A laminated film or sheet as set forth in claim 5, wherein said poly-4-methyl-1-pentene is a homopolymer of 4-methyl-1-pentene or a copolymer of 4-methyl-1-pentene with up to 20 mole % of an α-olefin having 2 to 20 carbon atoms.
 13. A laminated film or sheet as set forth in claim 5, wherein said propylene polymer is a crystalline homopolymer having an MFR of 1 to 200 g/10 min or a crystalline copolymer of propylene with up to 15 mole % of ethylene, 1-butene, 1-hexene, 4-methyl-1-pentene or 1-octene.
 14. A laminated film or sheet having at least three layers, which comprises(A) a layer consisting essentially of poly-4-methyl-1-pentene, (B) an intermediate layer of (1) a crystalline propylene polymer, (2) a polyester polymer, or (3) a poly-4-methyl-1-pentene having a lower melting point than said poly-4-methyl-1-pentene of layer (A), said intermediate layer (B) being laminated directly to layer (A), and (C) a paper layer laminated to the intermediate layer (B).
 15. The laminated film or sheet of claim 5 wherein the intermediate layer (B) is a crystalline homopolymer of propylene.
 16. The laminated film or sheet of claim 5 wherein the intermediate layer (B) is a crystalline copolymer of propylene with another olefin, wherein said another olefin is ethylene, 1-butene, 1-hexane, 4-methyl-1-pentene or 1-octene. 